cathodic
protection to repair balconies

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Construction and Maintenance CondoManagement SEPTEMBER 2002 Florida
Property Manager
We got lucky with our project.
The weather cooperated, allowing
us to put in long days and there
were no injuries on the job. As with
any major project, the unforeseen
will come up because there is no
way of know-
ing what
youre work-
ing with until
you get in
there. One
area that had
to be recon-
sidered was
the overlay on
the balconies. After the restoration
work was completed, the overlay on
the balcony didnt bond in all areas.
Reasons for this could have been
the surface wasnt prepared prop-
erly, the adhesive dried too quickly
or possibly the product was incor-
rect for the job. At any rate, the
overlay had to be chipped off and
the balconies needed to be re-
meshed. It was decided that all the
balconies had to be tiled and a spe-
cial thin-set grout was used. The
building looks neater and better
now because all the balconies have
tile. Southern Construction did a
great job. They took full responsibil-
ity and paid for the removal of the
overlay and tiling. Tiling is preferred
when CP is performed.
I have one piece of advice for
other property managers. Make
sure your residents are aware that
this is a very messy job. As with any
restoration project, there is a lot of
work involved. There will be a lot of
dust, commented Jeff LaFary, prop-
erty manager of Oceans Towers
South Condominium.
Ocean Towers South uses cathodic
protection to repair balconies
COVER STORY
BY PETER BROWNRIGG
n the spring of 2000, the owners
of Ocean Towers South Condo-
minium in Jupiter, FL, were faced
with a dilemma involving the major
I
restoration of their concrete balconies
and walkways. The boards president,
Aris Marziali was familiar with cathodic
protection (CP). Mr. Marziali took the
initiative to investigate options to protect
their building from future concrete dete-
rioration (known as spalling) which is
created by corrosion of the reinforcing
steel. After studying five different sys-
tems of protection, Mr. Marziali recom-
mended to the board to use Corrpro
Companies, Inc.s cathodic protection
system.
The mesh used is a conductor
of direct current. This offers
protection to the reinforcing
steel. The mesh also draws the
damaging salt away from the
steel and the concrete reverts
to an alkaline state. For a
more technical explanation,
contact a manufacturer that
deals with CP.
Before the CP system could be de-
signed, engineers visited the site to con-
duct a series of important tests at select
locations. The tests included the following:
Electrical Continuity:
For a reinforc-
ing bar to receive current under a CP
system, it must be electrically continu-
ous with the other steel bars in the con-
crete slab or it will not be protected. Dis-
continuous rebars are bonded (con-
nected) during the installation of the CP
system.
Resistivity of Existing Patches:
Since
the more than 20 year old building had
already gone through some sporadic re-
pairs, it was necessary to determine the
resistivity of the previous patching mate-
rials. Some patch materials have a
higher resistivity than the surrounding
original concrete, which could restrict Florida SEPTEMBER 2002
CondoManagement
Board president
We had a very serious problem
with spalling and decay. I was ex-
tremely surprised at the amount of
hidden problems. Corrosion is like
cancer. You dont know what youre
dealing with until youre actually
aware of it. Every year we did minor
repairs but that wasnt stopping the
decay. If we had just replaced the
damaged areas we were aware of, in
five years we would be right back
where we started. Cathodic protec-
tion bought us 15-20 years before
we have to think about spalling
problems again. Its more expensive
but worthwhile.
The process is very disruptive.
Our project only lasted ten months
but it was tough on the owners. Its
hard to live in a mess. The windows
had plywood over them. In addition
to the mess, the owners also had to
deal with a lot of noise. The old con-
crete had to be jackhammered out
and 40 workers doing their job is a
great disruption. We have a lot of
elderly and there was a concern for
their safety of just walking through
the area. Ideally, the owners should
find another place to live during the
process.
The owners also need to cooper-
ate and prepare their homes for the
work. They should clear three to
four feet from their sliding glass
door. They also need to be patient.
Communication is highly impor-
tant. We sent out 20 bulletins during
the course of the project to keep the
owners informed of the progress.
I stressed to the owners not to
pre-judge the work. I compared it to
a major surgery and you cant fall
apart because you see the stitches.
In the end youre better off. Our
building turned out better than ex-
pected and the residents are happy,
said Aris Marziali, board president
of Ocean Towers South.
The finished tile walkway
current flow. However, the results indi-
cated that the old patch materials actu-
ally had a slightly lower resistance than
the host (native) concrete, which indi-
cated that the CP current distribution
would not be compromised.
Polarization through Delaminations:
This test was performed to determine if
the CP system could stop corrosion
through areas of disbonded concrete.
This test utilized the half-cell potential
method and follows NACE (National As-
sociation of Corrosion Engineers)
guidelines.
Chloride and pH Samples:
Small cores
were drilled in the concrete at various lo-
cations and dust samples were taken and
sent to a lab for analysis.
The tests outlined above indicated
that the balconies and walkways, totaling
approximately 40,000 square feet, were
candidates for a CP system. Protection
of the re-bars would still be possible
through areas of delaminated concrete,
however, in consultation with the struc-
tural engineer for the project, it was rec-
ommended that all unsound concrete be
removed. Even with the elimination of
corrosion, the delamination can grow
and spall away from the existing slab
due to thermal effects, vibration, live
load, gravity, etc. If the board had cho-
sen to leave the delaminations in place
these areas would have been excluded
from the 15-year warranty.
The test results and recommenda-
tions set the course for a board vote to
add CP to the Ocean Towers South con-
crete repair project which started in
spring 2001 and took less than a year to
complete. The 42 unit owners of this
eleven-story building are now protected
by a 15-year joint and several warranties
between the CP manufacturer and the in-
stallation contractor against any
corrosion.
The never ending battle
against corrosion
If you live in a condominium like
Ocean Towers South with an oceanfront
exposure you are extremely vulnerable
to attack from airborne chlorides (salt)
which find their way to the structural
steel and cause corrosion. Up until re-
cently there was very little associations
could do to stop corrosion, only perhaps
to marginally slow down the process.
For years they have tried to combat cor-
rosion in the reinforcing steel by patch-
ing the delaminations and applying seal-
ers and membranes to their balconies or
walkways. Unfortunately, these tech-
niques only work for a short time, and
before long, the owners are faced with
another cycle of concrete repairs.
Key points and cost savings
The installation of a CP system does
not preclude the necessity of making con-
crete repairs or replacing seriously cor-
roded rebars. However, the extent to
which the repairs are made can be re-
duced somewhat depending on the cir-
cumstances and these can result in cost
savings.
Since waterproofing the balconies is
no longer required for protection of the
slabs, savings can also be made by elimi-
nating expensive urethanes and substi-
tuting either tile, as shown above, or a
more economic non-skid finish coating
(requires the ribbon anode in a slotted
system). Some condos are even going
back to carpet following CP installations.
Before selecting the most suitable
type of system for your condominium
consult a company with the right engi-
neering expertise, which should include
both structural and corrosion
experience.
To conclude, the most important
point to make is that a cathodic protec-
tion system, particularly the titanium
mesh anode, can be warranted for 15
years and may last for 25 years or more.
Peter Brownrigg, NCARB, is the South-
east Regional Manager, Concrete Services
Group of Corrpro Companies Inc. in Cocoa
Beach, FL.